Upgrade Using Plan B: Clean Install
If you prefer a cleaner installation of Mojave than what an in-place upgrade provides—specifically, one that gets rid of any disk errors and gives you a chance to weed out some types of user-created data—Plan B is what you should follow instead of Plan A. It’s also the right choice if you tried Plan A and encountered problems.
Much of Plan B is just like Plan A, so I refer to earlier discussions for some details. The differences come at the beginning (erasing your disk manually) and the end (using Setup Assistant to configure numerous settings and, optionally, transfer data from your bootable duplicate).
Start Up from Your Bootable Duplicate
Unlike Plan A’s in-place upgrade, Plan B requires a bootable duplicate of a Snow Leopard, Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, or High Sierra volume, which accomplishes three things:
You must erase the destination volume first. But you can’t erase the volume your Mac is currently running from, so you must start up from another volume.
You’ll need access to the Mojave installer too, of course, so it’ll be easiest if the volume you start up from contains the installer.
Once Mojave is installed, you’ll need your bootable duplicate (the one you created in Back Up Your Disk, remember?) connected in order to transfer your old data.
To start up from your duplicate:
Make sure the disk containing your duplicate is physically connected to your Mac (via Thunderbolt, USB, or FireWire).
Choose Apple > Restart.
Press and hold the Option key until a list of available startup volumes appears on screen.
Use the arrow keys to select your duplicate, and then press Return to boot from it.
Now that you’ve booted from what is about to be your old copy of macOS, you can erase your main disk and install Mojave onto it.
Erase Your Disk
Having started up from your duplicate, to erase your destination volume in preparation for Mojave, follow these steps:
Open Disk Utility (on your duplicate, in
/Applications/Utilities).In High Sierra or later, if only the volumes are visible in the sidebar and not the drive itself, choose View > Show All Devices.
In the sidebar, select the disk or partition you want to erase. (For a disk formatted as APFS, be sure to select the top-level icon, not an indented container or volume.)
On the toolbar, click the Erase button.
Make sure Format is set to Mac OS Extended (Journaled), and click Erase.
If you see a confirmation dialog, click Erase again. Disk Utility erases the disk, which normally takes just a few seconds. Click Done if prompted to do so when the Erase process is complete.
Choose Disk Utility > Quit Disk Utility.
You’re now ready to install Mojave on the empty volume.
Run the Installer
To proceed, make sure you’ve quit all running apps and then double-click the Install macOS Mojave icon in your /Applications folder or wherever else you put it. A window appears with one button: Continue. Click it!
The next few steps are identical to those for an in-place upgrade:
The Software License Agreement appears; click Agree, and then click Agree again in the confirmation dialog.
Now select your destination. If needed, click Show All Disks to display all available options and click the one you want to use.
With your desired destination volume selected, click Install.
Next, enter your administrator credentials and click Add Helper.
The installer begins copying files, a process that typically takes just a few minutes, but may take longer. Then, depending on your configuration, it may restart automatically or it may ask you to click a Restart button. After the restart, the main portion of the installation process occurs.
During the installation, you may want to Plan Your Next Vacation, but be sure to come back here once you’ve read that topic. As the installer progresses, your Mac will restart one or more times, but the startup chime (if your Mac model normally makes one) may not play. You’ll know the process has finished when the Welcome screen appears. That’s part of Setup Assistant, to which we now turn our attention.
Use Setup Assistant
Setup Assistant is a program that looks like a continuation of the Mojave installer. It runs automatically after Mojave restarts at the end of the installation process, and serves several purposes (some of which may not apply to you):
If applicable, it offers to transfer files from another Mac or PC, another volume (which can be your bootable duplicate; see Transfer Your Old Data, next), or a Time Machine backup.
It enables you to select your preferred country or region, and keyboard layout.
It configures your Mac to connect to the internet using a wireless network, if applicable.
It sets up your Mac to use your Apple ID for iCloud, iTunes, and other services.
It sets up an initial user account (with administrator privileges) if you’re not transferring an account from a backup or other source.
It lets you set your time zone, and the current date and time.
Your first task, on the Welcome screen, is to select a country or region and click Continue. You then see the Select Your Keyboard screen, which should be self-explanatory.
Setup Assistant next looks for a network connection. You see a screen called Select Your Wi-Fi Network. Select the network to which you want to connect and, if required, enter the password. Then click Continue. (If you connect to the internet some other way—or if you have no internet connection—click Other Network Options and select the appropriate option.)
A new Data & Privacy screen appears, showing a handshake icon. Read the screen to learn that this icon should appear when an Apple feature is asking for permission to use your personal information. If you want, click the Learn More link to read additional details. Finally, click Continue.
Next is the Transfer Information to This Mac screen (Figure 9), which enables you to transfer files from your bootable duplicate (as I cover next). If you’re tempted to skip this step in order to have a completely clean copy of Mojave, be sure to read the sidebar The Nuke-and-Pave Option.
Transfer Your Old Data
Setup Assistant includes “migration technology,” which is a fancy way of saying that it can copy important files from another computer or another volume in an intelligent way. We use it here to transfer the data from your bootable duplicate. (Mojave includes a stand-alone app called Migration Assistant—found in /Applications/Utilities—that can also transfer your data, but you probably won’t need to use it because Apple has integrated this tool’s capabilities into Setup Assistant.)
To transfer your old data to your new installation, work your way through the following screens:
Transfer Information to This Mac
Begin by selecting “From a Mac, Time Machine backup, or startup disk,” as shown in Figure 9, above. Click Continue. Now, select your bootable duplicate and click Continue.
Select the Information to Transfer
Now, select the kinds of data you want to transfer. The screen shows the size of each item, and the total size of the selected items, along with available space on your Mojave volume, updates automatically as you change your selections. (It may take a few minutes for the installer to initially display and calculate the size of each option.)
If the volume you’re transferring from has only one user account, you may see only three checkboxes, all selected by default: Applications, Documents & Data (with an accompanying Edit button), and Computer & Network Settings. If the volume has more than one user account, you’ll see a scrolling list that contains numerous items—again, all selected by default: Applications, each user account listed by name, an “Other files and folders” entry, and Computer & Network Settings.
Here’s an explanation of each option, and my recommendations:
Applications: This option transfers the contents of your previous
/Applicationsfolder (and its subfolders, such as Utilities), skipping any applications for which the Mojave installer has already loaded newer versions (Safari, Mail, and so on). Because you may find it tedious to reinstall your applications, leave this option selected, as it is by default.Documents & Data: If you have just one user account, you’ll see a checkbox labeled Documents & Data—this refers to the data in your user account. Click Edit to view its contents. In the dialog that appears, you can deselect any top-level folder within the account, except for the Library folder. Along with the visible top-level folders is a folder called Other Data. Apple doesn’t specify what this includes and my tests to find out have been inconclusive, so I suggest leaving it selected just in case it contains anything you need. Finally, there’s a checkbox labeled “Other files and folders.” This option refers to any files or folders at the root level of your old volume as well as anything in the
/Users/Sharedfolder. I suggest leaving this checkbox selected.User accounts: If you have more than one user account, each is shown at the top level of the list.
This list may include “users” that don’t have a conventional user account or home folder on your Mac, but which your Mac considers to have an account of a sort—people with whom you’ve shared files using System Preferences > Sharing, for example, or special low-level accounts added by software such as MacPorts or a VPN service. Some of these may display messages about having no home folder or having a home location that is no longer valid. Don’t worry about these messages; Setup Assistant is merely pointing out that these won’t create conventional user accounts, each with its own home folder. It’s best to leave such user accounts selected, even if they appear to contain no data.
Transferring a user means copying the user’s entire home folder, if any (
/Users/SomeUserName), to the Mojave volume; once a user is transferred, the user can log in without having to set up an account again. You should transfer all the existing users unless you have accounts that are no longer in use. You can, if you like, deselect any individual (top-level) folders within a user’s home folder to skip copying those to your Mojave volume. As for the unexplained Other Data folder (mentioned in the previous bullet point), the safest course is to leave it selected.If you don’t transfer at least one account, your screens later in these steps will be slightly different. Also, if you ever want to transfer any of these accounts, now is by far the best time to do so; copying files manually may cause you no end of grief and the Migration Assistant may not work as you’d hope.
Other files and folders: As in the single-user account setting described in the second bullet point, this option refers to any files or folders at the root level of your old volume as well as anything in the
/Users/Sharedfolder. I suggest leaving this checkbox selected.Computer & Network Settings: This category sometimes has up to three sub-items that you can select. Computer includes certain system-wide settings, such as sharing preferences, energy saver settings, and parental controls. Printers refers to your printer settings. Network includes the settings in your Network preference pane. I suggest leaving Computer & Network Settings (and all sub-items, if present) checked.
After making your selections, click Continue.
Certain newer Macs, including the MacBook Pro with Touch Bar and the iMac Pro, may display a new screen asking you to set passwords for each user account you’re migrating from your bootable duplicate to your new Mojave volume. This extra step is necessary because of Mojave’s added security features. You must set a password for at least one administrator account you want to migrate; accounts for which you don’t set a password can’t be copied to your Mojave volume. So, click Set Password next to an account name, enter and repeat a password for that user (which can be the same as the password that user currently uses), and click Set Password. Repeat for each administrator account you want to migrate.
If you’re asked to set up passwords and your bootable duplicate contains accounts for any non-administrators, the installer screen automatically assigns them a new, temporary password. Be sure to write this password down (or take a photo, or both), as it won’t be shown again. Alternatively, if you prefer, you can click Promote to Admin and follow the prompts to promote any or all of these users to administrators.
Transferring Your Information
Setup Assistant copies the selected items to your new Mojave volume—a process that may take just a few minutes or several hours, depending on how much data you are transferring. (And you should completely disregard any time estimates you see—as elsewhere in the installer, they’re wildly inaccurate.)
Incompatible Software
If Setup Assistant doesn’t notice any software conflicts with the files you’ve selected, you won’t see this screen. But if it does, this screen displays an Incompatible Software warning notice and the conflicting items are moved to an Incompatible Software folder at the top level of your startup volume or home folder. I say more about this in Review the Incompatible Software Folder. Click Continue to keep going.
Migration Complete
At the end of the migration process, a Migration Complete screen appears, stating that your data has been migrated and is ready to use. Click Quit to dismiss the window. At this point, your Mac should prompt you to log in, and then just a few questions remain.
Complete Setup Assistant
The next steps in Setup Assistant are mostly self-explanatory. Depending on which version of macOS you’re upgrading from, what information you transferred, and your previous settings, you may see one or more additional screens. (You’ll see even more screens if you’re performing a clean installation of Mojave without migrating any existing accounts—refer to The Nuke-and-Pave Option for an important recommendation.)
Here are some of the screens you may encounter—not necessarily in this order. (Most of them are identical to those described earlier in Finish Setup Assistant, so I describe them only briefly here.) After each one, click Continue to advance through the remaining screens:
Choose Your Look: Click Light or Dark, depending on how you like your coffee (or whether you consider yourself a Jedi or a Sith).
Sign in with Your Apple ID: Depending on the circumstances, you may be asked only for your password, or for both your Apple ID and your password. In the latter case, enter the Apple ID you want to use for iCloud and iTunes, along with your password; or, if you prefer to use a different one for each, if you see a “Use different Apple IDs for iTunes and iCloud?” link, click it and follow the prompts. (This link appears only under certain conditions.)
Verify Your Identity: If you’ve enabled Apple’s Two-factor Authentication or Two-step Verification for your Apple ID, an extra screen may ask you to perform a second verification step.
Terms and Conditions: Yes, you already agreed to the Mojave license, but this screen includes additional legalese.
Express Set Up: To accept Apple’s default settings for location services, analytics, and Siri (turning on all three), click Continue on this screen. Or, to decide about each of these features individually, click Customize Settings and work your way through their respective screens (described ahead).
Enable Location Services: If you hadn’t previously enabled Location Services, which is used for iCloud’s Find My Mac feature, Maps, Spotlight suggestions, and numerous other things, a dialog appears asking if you’d like to do so. Check “Enable location services on this Mac” if you like (if you don’t check it, you can enable this setting later in System Preferences > Security & Privacy > Privacy > Location Services), or click the “About Location Services & Privacy” link to learn more.
Analytics: Mojave can automatically send diagnostic and usage data to Apple and/or third-party developers to help them track down the causes of crashes and other bugs you may encounter. This information is anonymous and doesn’t contain personal data.
If you want to send this troubleshooting data in the event that a problem occurs, select Send Diagnostics & Usage Data to Apple. With that selected, you may also select Share Crash Data with App Developers. (You can’t share crash data with app developers unless you also share diagnostic data with Apple.)
Siri: This screen has a single checkbox, Enable Ask Siri, which is selected by default. Leave it selected to enable Siri voice control after Mojave is installed, or deselect it to disable Siri. (You can always enable or disable Siri later—go to System Preferences > Siri once Mojave is up and running.)
iCloud Drive: If all your devices are using (or are about to be using) Mavericks or later or iOS 8 or later, select Upgrade to iCloud Drive. Otherwise select Not Now.
All your files in iCloud: Mojave may ask if you want it to store all the files from your Documents and Desktop folders in iCloud Drive. I recommend that you deselect “Store files from Documents and Desktop in iCloud Drive” for now, and if you decide later that you want that feature, you can turn it on. To do so, go to System Preferences > iCloud, select the iCloud Drive checkbox if it is not already selected, click the Options button next to iCloud Drive, select Desktop & Documents Folders, and click Done.
FileVault Disk Encryption: If FileVault was enabled on the volume you’re migrating data from, you’ll probably want it enabled on the new volume too, but it isn’t encrypted by default. So if you see a screen prompting you to enable FileVault, I recommend saying yes. This screen has two checkboxes:
Turn on FileVault disk encryption: This is selected by default; leave it selected to enable FileVault.
Allow my iCloud account to unlock my disk: This is also selected by default, but I recommend unchecking it, because with it checked, anyone who got access to your iCloud account could potentially decrypt your Mac’s disk. If you do uncheck it, then on the next screen (after you click Continue) will be a long recovery key, which you’ll need if you ever forget your Mac’s password. Be sure to write this down, or better yet, snap a photo of the screen.
Touch ID: If you’re installing Mojave onto a MacBook Pro with a Touch Bar, the installer prompts you to set up Touch ID. You can either do so now or click Continue to skip this, and set it up later in System Preferences > Touch ID.
Setting Up Your Mac: When you see this screen, you know Setup Assistant has stopped asking you questions. It’ll disappear on its own in a moment and you’ll be looking at your Mojave desktop.
Whether Setup Assistant displays just one screen or many, Mojave itself may display any number of dialogs and alerts the first time you use it, such as password prompts, software update messages, and requests to enable various features. To learn how to deal with these and other immediate concerns, see Perform Post-Installation Tasks.